[osg-users] getCamera matrix in update callback

[Trajce Nikolov]

Hi,

with the following setup I expect to have a line from the center of the
screeen to the point hard coded. It not that case. Any ideas?

Thanks

this is geode update callback


class UpdateCallback : public osg::NodeCallback
{
public:
UpdateCallback(osgViewer::Viewer* viewer)
 : mViewer(viewer)
{
}

virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
{
 osg::Geode* geode = dynamic_castosg::Geode*(node);
if (!geode) return;

geode-removeDrawables(0,geode-getNumDrawables());

osg::Geometry* geometry = new osg::Geometry;
 geode-addDrawable(geometry);

osg::Vec3 eye;
osg::Vec3 center;
 osg::Vec3 up;
mViewer-getCamera()-getViewMatrixAsLookAt(eye,center,up);

osg::Vec3Array* verts = new osg::Vec3Array;
verts-push_back(eye);
 verts-push_back(osg::Vec3(20,20,20));
geometry-setVertexArray(verts);

osg::Vec4Array* colors = new osg::Vec4Array;
colors-push_back(osg::Vec4(0,1,0,1));
 geometry-setColorArray(colors);
geometry-setColorBinding(osg::Geometry::BIND_OVERALL);

geometry-addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::LINES,0,verts-size()));

float radius = 0.8f;
 float height = 1.0f;

osg::TessellationHints* hints = new osg::TessellationHints;
 hints-setDetailRatio(0.5f);

geode-addDrawable(new osg::ShapeDrawable(new
osg::Sphere(osg::Vec3(20.0f,20.0f,20.0f),radius),hints));

geode-dirtyBound();

}
protected:
 osgViewer::Viewer* mViewer;
};

Nick

http://www.linkedin.com/in/tnick
Sent from Devlet, Ankara, Turkey
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Re: [osg-users] getCamera matrix in update callback

[Paul Martz]

You appear to be drawing it from the eye to a hardcoded point. I think 
you need to compute the location of a point directly in front of the 
eye, and draw the line from there to the hardcoded point (if I am 
understanding what you are trying to do correctly).


If I remember correctly, getViewMatrixAsLookAt takes an implicit 
parameter to define the distance from the eye to the center point that 
it returns. So, if you supply that distance, the you should be able to 
draw a line from center to a hardcoded value.


Paul Martz
Skew Matrix Software LLC
_http://www.skew-matrix.com_ http://www.skew-matrix.com/
+1 303 859 9466



Trajce Nikolov wrote:

Hi,

with the following setup I expect to have a line from the center of the
screeen to the point hard coded. It not that case. Any ideas?

Thanks

this is geode update callback


class UpdateCallback : public osg::NodeCallback
{
public:
UpdateCallback(osgViewer::Viewer* viewer)
 : mViewer(viewer)
{
}

virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
{
 osg::Geode* geode = dynamic_castosg::Geode*(node);
if (!geode) return;

geode-removeDrawables(0,geode-getNumDrawables());

osg::Geometry* geometry = new osg::Geometry;
 geode-addDrawable(geometry);

osg::Vec3 eye;
osg::Vec3 center;
 osg::Vec3 up;
mViewer-getCamera()-getViewMatrixAsLookAt(eye,center,up);

osg::Vec3Array* verts = new osg::Vec3Array;
verts-push_back(eye);
 verts-push_back(osg::Vec3(20,20,20));
geometry-setVertexArray(verts);

osg::Vec4Array* colors = new osg::Vec4Array;
colors-push_back(osg::Vec4(0,1,0,1));
 geometry-setColorArray(colors);
geometry-setColorBinding(osg::Geometry::BIND_OVERALL);

geometry-addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::LINES,0,verts-size()));

float radius = 0.8f;
 float height = 1.0f;

osg::TessellationHints* hints = new osg::TessellationHints;
 hints-setDetailRatio(0.5f);

geode-addDrawable(new osg::ShapeDrawable(new
osg::Sphere(osg::Vec3(20.0f,20.0f,20.0f),radius),hints));

geode-dirtyBound();

}
protected:
 osgViewer::Viewer* mViewer;
};

Nick

http://www.linkedin.com/in/tnick
Sent from Devlet, Ankara, Turkey





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Re: [osg-users] getCamera matrix in update callback

[Trajce Nikolov]

Hi Paul,

I did that as well. Instead of drawing the line from the eye I draw it from
the center (the result from getViewMatrixAsLookAt).

when the scene is static, means no camera move, it draws from the centar,
when I move the scene it jums all around. Please give it a try and let me
know if that is a bug somewhere or I am doing something wrong

Thanks!
Nick

http://www.linkedin.com/in/tnick
Sent from Ünalan, İstanbul, Turkey

On Sat, Dec 19, 2009 at 8:42 PM, Paul Martz pma...@skew-matrix.com wrote:

 You appear to be drawing it from the eye to a hardcoded point. I think you
 need to compute the location of a point directly in front of the eye, and
 draw the line from there to the hardcoded point (if I am understanding what
 you are trying to do correctly).

 If I remember correctly, getViewMatrixAsLookAt takes an implicit parameter
 to define the distance from the eye to the center point that it returns.
 So, if you supply that distance, the you should be able to draw a line from
 center to a hardcoded value.

 Paul Martz
 Skew Matrix Software LLC
 _http://www.skew-matrix.com_ http://www.skew-matrix.com/
 +1 303 859 9466



 Trajce Nikolov wrote:

 Hi,

 with the following setup I expect to have a line from the center of the
 screeen to the point hard coded. It not that case. Any ideas?

 Thanks

 this is geode update callback


 class UpdateCallback : public osg::NodeCallback
 {
 public:
 UpdateCallback(osgViewer::Viewer* viewer)
  : mViewer(viewer)
 {
 }

 virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
 {
  osg::Geode* geode = dynamic_castosg::Geode*(node);
 if (!geode) return;

 geode-removeDrawables(0,geode-getNumDrawables());

 osg::Geometry* geometry = new osg::Geometry;
  geode-addDrawable(geometry);

 osg::Vec3 eye;
 osg::Vec3 center;
  osg::Vec3 up;
 mViewer-getCamera()-getViewMatrixAsLookAt(eye,center,up);

 osg::Vec3Array* verts = new osg::Vec3Array;
 verts-push_back(eye);
  verts-push_back(osg::Vec3(20,20,20));
 geometry-setVertexArray(verts);

 osg::Vec4Array* colors = new osg::Vec4Array;
 colors-push_back(osg::Vec4(0,1,0,1));
  geometry-setColorArray(colors);
 geometry-setColorBinding(osg::Geometry::BIND_OVERALL);

 geometry-addPrimitiveSet(new
 osg::DrawArrays(osg::PrimitiveSet::LINES,0,verts-size()));

 float radius = 0.8f;
  float height = 1.0f;

 osg::TessellationHints* hints = new osg::TessellationHints;
  hints-setDetailRatio(0.5f);

 geode-addDrawable(new osg::ShapeDrawable(new
 osg::Sphere(osg::Vec3(20.0f,20.0f,20.0f),radius),hints));

 geode-dirtyBound();

 }
 protected:
  osgViewer::Viewer* mViewer;
 };

 Nick

 http://www.linkedin.com/in/tnick
 Sent from Devlet, Ankara, Turkey



 

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